As stated by Braun in his published US patent application published Sep. 27, 2007 under publication no. 2007/0221385 and entitled Apparatus and Method for Forming Stands, the entire disclosure of which is incorporated herein by reference, various ground drilling operations are known such as exploring and/or extracting oil from subterranean deposits. The drilling operation is conducted on a drill rig comprising a raised drilling platform located above the drilling location. A derrick is provided on the platform to raise, support and rotate a drill string. A drill string includes a drill bit for boring into the ground. As the drilling operation continues, tubular members, commonly referred to as “tubulars” (and referred to herein alternatively as pipes or singles) are connected in an end to end manner to form a drill string. Tubulars are commonly about 30 feet in length and have opposing female and male ends. The ends are threaded in a complementary manner so that opposing male and female ends can be joined together.
The addition of a tubular to an existing drill string is a relatively time consuming and dangerous procedure. Tubulars are provided on a rack from which they are individually rolled onto a horizontal support, such as a catwalk. Both the rack and catwalk are generally located adjacent to the drilling platform with the catwalk being generally positioned perpendicular to the platform. Once on the catwalk, one end of the tubular is attached to a hoist connected either directly of indirectly to the derrick and raised to a vertical position on the drilling platform. The lower end of the tubular is then oriented over the existing drill string and connected to the terminal, surface end thereof. Following connection of the tubular to the drill string and “torquing” to establish a tight connection, the drilling operation is continued. As indicated above, tubulars are generally about 30 feet (10 m) in length. As such, the frequency of adding tubulars to the drill string is high and, therefore, the efficiency of the drilling operation is hampered. In addition, the above described manipulation of the tubulars often requires manual handling and, therefore, increases the risks to the drill rig personnel.
In order to increase the efficiency of the drilling operation, various methods have been proposed to pre-connect at least two tubulars, to form a “stand”, prior to connection to the drill string. Such a process is often referred to as “standbuilding”. As will be appreciated, such pre-connection step involving two tubulars will reduce by half the number of connections required to be made to the drill string and, therefore, allows the drilling process to continue with fewer interruptions. An example of such a standbuilding procedure is provided in related U.S. Pat. Nos. 6,976,540 and 6,997,265. In these references, a tubular is rolled from a rack onto a ramp positioned adjacent the drilling platform. One end of the tubular is raised by a hoist to a vertical orientation above the drilling platform. The tubular is then inserted into an opening in the drilling platform adjacent to the existing drill string. A further tubular is then vertically hoisted and aligned above the first tubular. The opposing ends are of the two tubulars are then connected together to form a vertical, dual tubular stand. The stand is then raised and secured to the drill string. During formation of the stand, the drilling operation is continued without interruption.
Another example of a standbuilding operation is provided in U.S. Pat. No. 6,705,414. In this reference, a stand is formed on a horizontal catwalk associated with a drilling platform. According to the disclosed method, two tubulars are positioned end to end on the catwalk. A “bucking machine” is then used to join the two tubulars. The bucking machine includes jaws that grasp and axially rotate the tubulars in opposite directions so as to engage the threads on the respective ends and to torque the connection to the desired value. Two stands are formed in this manner, which are then loaded onto a “trolley”. The trolley, carrying the two stands, is hoisted onto the drill rig platform and oriented vertically. The stands are then removed from the trolley and either connected to the drill string or stored in the vertical position for later connection to the drill string.
In the prior art applicant is also aware of U.S. Pat. Nos. 6,976,540 and 6,997,265 to Berry for his Method and Apparatus for Offline Standbuilding, and U.S. Pat. No. 7,228,919 to Fehres et al. for a Pivoting Pipe Handler for Off-line Make-up of Drill Pipe Tubulars.
In the prior art of which applicant is aware, support is lacking for the length of pipe stand during hoisting from the horizontal to the vertical where the pipe stand is built horizontally in advance of hoisting.